Clogged turbo banjo screens aren't a concern for your motor, so no need to worry there. They're not really a concern for modern turbo Subaru's in general actually.
The 2.5 and 2.0 Subaru motors seem to make a noticeable amount of timing chain noise upon a dry startup (have two in the family now) perhaps that's what you're hearing. You also mentioned that you're new to Subaru's, and maybe you're just experiencing what a cold flat subaru engine sounds like?
It's a unique sound and definitely louder than most other designs and I can completely see how people would think they have a lifter tick or piston slap issue as the motor reaches operating temps, but it's almost always perfectly normal. We have a crosstrek, forrester XT and outback 3.6 in the family and they ALL sound like that when cold upon startup and are even inherently a bit louder than other designs when at temp even.